The inventors herein have recognized that valves that may be deactivated, including electromagnetically actuated valves, present an opportunity to improve fuel economy and vehicle emissions by presenting valve control options that have not been previously available. However, since the valves may be individually controlled, configured in various patterns, and employed in various numbers per cylinder, the control possibilities and permutations seem nearly endless.
One method to control intake and exhaust valve operation during engine operation is described in U.S. Pat. No. 6,374,813. This method presents a means to control electromagnetically actuated valves to promote EGR control. The approach selects different valve modes and patterns to regulate internal EGR, i.e., EGR flow through a cylinder as opposed to EGR routed to the intake manifold. Valves are operated independently and control is based on operating conditions of the engine. Further, the disclosure also describes several valve configurations that may be operated in one or more operational modes to promote cylinder air charge swirl.
The above-mentioned method also can have several disadvantages. Namely, the approach selects valve mode based simply on engine speed, load, and desired EGR. The approach does not consider many other constraints that can affect valve mode selection. Further, the approach does not address valve selection in alternate cylinder modes, i.e., six-stroke, twelve-stroke, or cylinder deactivation. In addition, even if one of ordinary skill in the art attempted to extend the method to include additional modes, complexity would increase dramatically using the prior art approach.